AB 13:215-223 (2011)  -  DOI: https://doi.org/10.3354/ab00359

Sea urchin fecal production and accumulation in a rocky subtidal ecosystem

Leah K. Sauchyn1,*, Jean-Sébastien Lauzon-Guay2, Robert E. Scheibling1

1Biology Department, Dalhousie University, Halifax, Nova Scotia B3H 4J1, Canada
2Institut Maurice-Lamontagne, Fisheries and Oceans Canada, Mont-Joli, Québec G5H 3Z4, Canada

ABSTRACT: We used a spatial model of destructive grazing of kelp beds by dense aggregations (fronts) of sea urchins Strongylocentrotus droebachiensis, together with measures of sea urchin absorption efficiency and fecal degradation rate, to predict rates of fecal production and accumulation during the transition from a kelp bed to a barrens state in a rocky subtidal ecosystem of Nova Scotia, Canada. The rate of fecal production as dry mass reached 9.17 g m–2 d–1 at 10 yr after the formation of a grazing front, with associated rates of carbon and nitrogen production of 2.12 g C m–2 d–1 and 0.21 g N m–2 d–1. Fecal production rate exceeded the rates of physical, chemical, and microbial degradation, such that up to 193.6 g of feces, 70.2 g of C, and 4.0 g of N accumulated per linear m of front after 10 yr. The extent of sea urchin grazing fronts along the Atlantic coast of Nova Scotia was estimated at 280 km in 2000, which translates to a total fecal production rate of 6423 kg of feces d–1 and an accumulation of 54200 kg of feces after 10 yr of front formation, based on our model. This temporally variable flux of organic matter likely has a profound effect on adjacent deeper-water macrobenthic communities utilizing the feces as a food source.

KEY WORDS: Fecal production · Organic matter flux · Degradation · Kelp bed · Sea urchin · Strongylocentrotus droebachiensis

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Cite this article as: Sauchyn LK, Lauzon-Guay JS, Scheibling RE (2011) Sea urchin fecal production and accumulation in a rocky subtidal ecosystem. Aquat Biol 13:215-223. https://doi.org/10.3354/ab00359

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